By definition a retroreflective material is a material which when engaged by a beam of light will reflect the light directly back to the location of the light source. Such a material is commonly used in roadways and aircraft runways to define the outer edges and/or center line of the roadway so that when engaged by headlights of a vehicle at night, the operator of the vehicle will be able to visually perceive and determine the roadway edges and/or center line.
Retroreflective material is also marketed in the form of a thin film, usually with an adhesive backing on one surface thereof, whereby the retroreflective film may be adhered to a person's clothing for safety purposes, i.e. to make that person more readily discernible at night by the headlights of approaching vehicles, or for securing to any other surface where retroreflective characteristics are desired, such as roadsigns, etc. U.S. Pat. No. 3,849,804 dated Nov. 26, 1974; U.S. Pat. No. 3,276,416 dated Oct. 4, 1966; and U.S. Pat. No. 3,499,416 dated Mar. 10, 1970, are representative of prior art patents that suggest the attachment of light reflecting material to clothing, automobilles, safety belts, etc., although it is not clear whether the reflective material used in these patents is usually retroreflective material.
In any event, there are numerous disadvantages to having to secure a light reflecting film to fabric material, and specifically, a problem exists in effecting a secure attachment of the film to the fabric because of the flexibility of the latter, there is always the danger that the film will inadvertently become detached, and additionally one must necessarily suffer the expense and inconvenience of separately purchasing the light reflective film, and then going through the steps of cutting the reflective film to the desired size or configuration and then attaching it to the fabric or garment, etc.
It therefore would be highly desirable to provide a yarn which includes as a part thereof retroreflective fibers so that when said yarn is woven, knitted or spun to provide a finished fabric and/or garment, the latter will inherently have retroreflective characteristics. Such garments would have obvious utility for persons who jog in the nighttime, policemen on traffic duty in heavily congested areas at nighttime, etc. The problem, however, is that the retroreflective film presently being marketed does not have sufficient body or strength so as to be effectively handled if cut or slit into the form of elongated strands of fibers. Specifically, the elasticity of the material as well as the inherent weakness thereof preclude effective use of such strands, even as part of a composite yarn, for conventional weaving, knitting, spinning, etc.
It is therefore the primary object of the present invention to provide a method of making a continuous thread-like fiber of retroreflective material which nevertheless has sufficient strength and body so that it may be effectively combined with other fibers to provide a composite yarn which has retroreflective characteristics, which composite yarn may then be conventionally woven, knitted or spun to provide a fabric or garment having retroreflective characteristics. The present invention achieves this objective by laminating the thin film of retroreflective material to an even thinner polyester supporting film, the polyester supporting film adding sufficient strength and body to the laminate so that the latter may be effectively slit or cut to form elongated thread-like strands or fibers of, ribbon-like substantially rectangular cross-section configuration having retroreflective characteristics.